Conventionally, the Internet offered a single QOS, i.e. only a best-effort type service that is equipped with a delay characteristic depending on the available bandwidth and instantaneous load. The control of QOS for each application is conducted by setting the network infrastructure properly. The concerned delay guarantee system by the Share Ride and timer can be estimated to satisfy the minimum bandwidth guarantee by only setting the standard frame length and time-out value suitably for each aggregated flow at each node, when handling only the best-effort data traffic, which occupies currently the majority of the Internet.
Referring to FIG. 1, the routing operation in optical network to supply only delay guarantee by the Share Ride and timer is explained. In a transmission network between an originating edge node (1b) and a destination edge node (1b), the delay is maximized when there occurs super frame construction waiting at all via core nodes (1c) located on the transmission path between the originating edge node (1b) and destination edge node (1b), and there occurs time out at all the nodes.
In this case, time delays of n×Td are accumulated between the originating edge node and destination edge node of optical network. Meanwhile, a n-stage connection and a time-out time of Td for super frame construction waiting are assumed, and the fixed delay in device is neglected.
Japanese patent application laid-open No. 6-334680 (1994) discloses a communication method where both of communication for audio, image signal etc. that needs the guarantee of band and non-band-guarantee type communication for data etc. that needs the utilization of band by the multiplexing guarantee can be handled by a single communication protocol, as well as handling communication with a limitation in fluctuation delay time and data communication with high burst characteristic. In detail, means for controlling the calling reception between communication nodes are provided and a connection at ATM layer is set. Here, the connection is end-to-end transmission path and corresponds to VC (virtual channel).
Japanese patent application laid-open No. 10-93624 (1998) discloses a packet transfer network where as a measure of convergence in network, not relative network queuing delay but absolute network queuing delay is used to provide an extension adaptive speed base convergence control system. In detail, to measure the sum of end-to-end transfer delay, test sample traffic is defined and the dynamic control of transmission speed is conducted.
However, in Japanese patent application laid-open No. 6-334680, to give the connection newly, known software processing by signaling protocol is available. However, the temporal overhead of this software processing is significantly longer than the time for packet transmission.
Also, when conducting the dynamic control of transmission speed by the algorithm in Japanese patent application laid-open No. 10-93624, the scale of hardware increases. Namely, to calculate the minimum cell speed, round-trip time, the time-out maximum value of various timers, lowest-speed link capacity etc., it is necessary to dispose a message exchanging means to communicate the condition of load between nodes and a timer with good accuracy at each node.
Further, since a real time service such as audio traffic is characterized by a low packet delay variation and a very low packet loss, the delay guarantee at network level cannot be obtained by only the method above-mentioned.